ARS | Publication request: Nitrogen Partitioning and Utilization in Corn Cropping Systems: Rotation, N Source, and N Timing

Submitted to: European Journal of Agronomy
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 29, 2010
Publication Date: N/A

Interpretive Summary: The amount of nitrogen and forms of nitrogen and the location of nitrogen in the plant (i.e. nitrogen in the grain or in the leaves and stem; also known as nitrogen partitioning) can partially control plant productivity. This study was conducted to estimate how the nitrogen fertilizer source, timing of nitrogen fertilizer application, and crop rotation affect the amount of dry matter and the nitrogen partitioning parameters in corn. We measured the yield, aboveground dry matter accumulation and the carbon and nitrogen concentrations of corn continuously cropped or in rotation with soybean. The fertilizer sources were urea-ammonium nitrate or liquid swine manure applied either in the spring or in the fall. Of the assessed nitrogen partitioning parameters, the nitrogen utilization showed the highest association with corn yield. Across treatments, 72% of the increase in nitrogen utilization could be attributed to increases in nitrogen uptake. Both nitrogen uptake and nitrogen utilization were driven by type of nitrogen fertilizer. Furthermore, corn nitrogen utilization and yield were 10 to 13% greater within the corn-soybean rotation, suggesting that a shift in land use from crop rotations into more continuous corn due to increasing demand for corn grain may impose additional challenges for enhancing plant nitrogen nutrition and sustaining yield.

Technical Abstract: Nitrogen partitioning and utilization can partly control plant productivity. This study was conducted to estimate dry matter (DM) and N partitioning parameters in corn (Zea mays L.) as affected by N source, N timing, and crop rotation. We quantified yield by combine, aboveground DM accumulation [residues (stalk + cob) and grain], and C and N concentrations at growth stage R6 of corn continuously cropped (CC) or in rotation with soybean [Glycine max (L.) Merr.] (CS) and fertilized with side-dressed urea-ammonium nitrate (UAN) or with liquid swine manure applied in either spring (SM) or fall (FM). Of the assessed N partitioning parameters, N utilization showed the highest association with yield (r = 0.94***). Across treatment means, 72% of these increases in N utilization could be attributed to increases in N uptake. On the contrary, N harvest index (NHI) exhibited nearly constant values across experimental units, and therefore, NHI showed a minor relative contribution to variations in N utilization, thus supporting the basic premise of low NHI dependency on environment or management. Both N uptake and N utilization were driven by type of N addition (UAN > manure). Also, corn N utilization and yield were greater (10-13%) within the corn-soybean rotation, suggesting that a shift in land use from crop rotations into more continuous corn due to increasing demand for corn grain may impose additional challenges for enhancing plant N nutrition and sustaining yield.